Further Studies of Ultraviolet-sensitive Mutants of Escherichia coli Strain B

A group of twelve ultraviolet-sensitive mutants has been isolated after u.v. irradiation of Escherichia coli strain b. The use of crystal violet during irradiation and subsequent growth appears to increase the frequency of such mutants among colonies formed by surviving cells. This effect may be due to post-irradiation selection. Eleven of the mutants were more crystal violet resistant than their parent. The mutants were compared by determining their u.v. survival curves, the extent of elongation after u.v. irradiation, their ability to repair u.v. induced damage to bacteriophage T1, and their resistance to furacin. They comprised nine different phenotypes. In all but one case, the mutants differed from the parent in more than one property.